When hiring staff for your company, some people you bring on are obvious rock stars. Others may be gambles. But you want to avoid hiring disasters at all cost.

At the memorial service this week for former South African president and anti-apartheid champion Nelson Mandela, event organizers hired an interpreter to translate what was being said for viewers who are hearing impaired. What they got, however, was schizophrenic man who translated words into gibberish.

In a press conference following the event, A South African deputy cabinet minister said "a mistake happened" in the hiring of the interpreter.

Employers need to be sensitive when hiring people with health conditions but this goes to show that going the extra mile when screening your job candidates is an absolute must. In this situation, a schizophrenic man was standing alongside some of the most powerful and important people in the world, including U.S. President Barack Obama.

Ask open-ended questions.
Go beyond simple questions that elicit one-word or obvious responses. Asking open-ended questions can get candidates to offer additional details about themselves and their work history.

"Tell me about your last job" is one example. Once the candidate responds you can ask follow up questions like "Why did you do that?" to get more detail.

Look beyond the facade.
Some job candidates look good on paper. Some still look good after answering some textbook interview questions. Dig deeper by asking unusual or more specific questions. The person's answers can give you better insight about how he or she will react under pressure and hint whether the person might be a solid fit for the culture of your team.

Also pay attention to nonverbal cues, such as attire and whether the person seems attentive. Theses can tell you a lot about a person, too.

Check references.
This is big. A person can sell him or herself to you any way he or she wants. The best way to verify that this information is accurate is by calling and speaking with former employers and colleagues. This can also help provide deeper insight into the person's work ethic and ability to work with a team.

Ask that your candidates provide references when they arrive for the interview. If he or she is evasive, this should raise a serious flag.